High Flow Fiber-Reinforced Propylene Composition Having Low Emissions

ABSTRACT

A fiber-reinforced polymer composition that contains a polymer matrix and a plurality of long reinforcing fibers that are distributed within the polymer matrix is provided. The polymer matrix contains a propylene polymer and constitutes from about 30 wt. % to about 90 wt. % of the composition. The fibers constitute from about 10 wt. % to about 70 wt. % of the composition. Further, the polymer composition exhibits a spiral flow length of about 450 millimeters or more as determined in accordance with ASTM D3123-09 and a volatile organic content of about 100 micrograms per gram or less as determined by VDA 277.

RELATED APPLICATIONS

The present application is a continuation of U.S. application No.15,865,306, filed on Jan. 9, 2018, which claims priority to U.S.Provisional Applications Ser. No. 62/444,583, filed on Jan. 10, 2017,62/250,662, filed on Jun. 16, 2017, and 62/570,696, filed on Oct. 11,2017, which are incorporated herein in their entirety by referencethereto.

BACKGROUND OF THE INVENTION

Long fiber-reinforced polypropylene compositions are often employed inmolded parts to provide improved mechanical properties. Typically, suchcompositions are formed by a process that involves extruding a propylenepolymer through an impregnation die and onto a plurality of continuouslengths of reinforcing fibers. The polymer and reinforcing fibers arepulled through the die to cause thorough impregnation of individualfiber strands with the resin. Despite the benefits that can be achievedwith such compositions, it is often difficult to effectively employ themin parts having a very thin wall thickness due to the high meltviscosity of conventional propylene polymers. While various attemptshave been made to improve the flow properties of propylene polymers bylowering their melt viscosity, these efforts tend to have an adverseimpact on the organic volatile content that is emitted by thecomposition. As such, a need currently exists for a fiber-reinforcedpropylene composition for use in forming shaped parts that can exhibitgood flow properties and yet still retain minimal volatile emissions.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, afiber-reinforced polymer composition is disclosed that contains apolymer matrix and a plurality of long reinforcing fibers that aredistributed within the polymer matrix. The polymer matrix contains apropylene polymer and constitutes from about 30 wt. % to about 90 wt. %of the composition. The fibers constitute from about 10 wt. % to about70 wt. % of the composition. Further, the polymer composition exhibits aspiral flow length of about 450 millimeters or more as determined inaccordance with ASTM D3123-09 and a volatile organic content of about100 micrograms or less per gram as determined by VDA 277.

In accordance with another embodiment of the present invention, anautomotive part is disclosed that comprises a fiber-reinforced polymercomposition comprising a polymer matrix that contains a propylenepolymer and a plurality of long reinforcing fibers that are distributedwithin the polymer matrix. The part exhibits a spiral flow length ofabout 450 millimeters or more as determined in accordance with ASTMD3123-09, and the part exhibits a volatile organic content of about 50μgC/g or less as determined in accordance with VDA 277:1995.

Other features and aspects of the present invention are set forth ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIG. 1 is a schematic illustration of one embodiment of a system thatmay be used to form the fiber-reinforced polymer composition of thepresent invention;

FIG. 2 is a cross-sectional view of an impregnation die that may beemployed in the system shown in FIG. 1;

FIG. 3 is a perspective view of one embodiment of an automotive interiorthat may contain one or more parts formed from the fiber-reinforcedpolymer composition of the present invention; and

FIG. 4 is a perspective view of the door module shown in FIG. 3 and thatmay be formed from the fiber-reinforced polymer composition of thepresent invention.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention.

Generally speaking, the present invention is directed to afiber-reinforced composition for use in a shaped part (e.g., injectionmolded part) that contains a plurality of long reinforcing fibersdistributed within a polymer matrix that contains a propylene polymer.Long fibers may, for example, constitute from about 10 wt. % to about 70wt. %, in some embodiments from about 15 wt. % to about 65 wt. %, and insome embodiments, from about 20 wt. % to about 60 wt. % of thecomposition. Likewise, the polymer matrix typically constitutes fromabout 30 wt. % to about 90 wt. %, in some embodiments from about 35 wt.% to about 85 wt. %, and in some embodiments, from about 40 wt. % toabout 80 wt. % of the composition. The polymer matrix contains at leastone propylene polymer, which may have a high degree of flow in that ithas a relatively high melt flow index, such as about 150 grams per 10minutes or more, in some embodiments about 180 grams per 10 minutes ormore, and in some embodiments, from about 200 to about 500 grams per 10minutes, as determined in accordance with ISO 1133-1:2011 (technicallyequivalent to ASTM D1238-13) at a load of 2.16 kg and temperature of230° C.

Due to the high fluidity of the fiber-reinforced composition, relativelythin shaped parts (e.g., injection molded parts) can be readily formedtherefrom. For example, such parts may have a thickness of about 4millimeters or less, in some embodiments about 2.5 millimeters or less,in some embodiments about 2 millimeters or less, in some embodimentsabout 1.8 millimeters or less, and in some embodiments, from about 0.4to about 1.6 millimeters (e.g., 1.2 millimeters). When forming aninjection molded part, for instance, a relatively high “spiral flowlength” can be achieved. The term “spiral flow length” generally refersto the length reached by the flow of the composition in a spiral flowchannel when it is injected at constant injection temperature andinjection pressure from a central gate of a mold in which the spiralflow channel is formed. The spiral flow length may, for instance, beabout 450 millimeters or more, in some embodiments about 600 millimetersor more, and in some embodiments, from about 650 to about 1,000millimeters, as determined in accordance with ASTM D3123-09. Theinjection pressure that may be employed to shape the fiber-reinforcedcomposition into an injection molded part may also be relatively low,such as about 750 bar or less, in some embodiments about 700 bar orless, and in some embodiments, from about 300 to about 650 bar.

Conventionally, it was believed that compositions having such a highfluidity could not also possess sufficiently low emissions of volatileorganic compounds. As used herein, the term “volatile compounds” or“volatiles” generally refer to organic compounds that have a relativelyhigh vapor pressure. For example, the boiling point of such compounds atatmospheric pressure (1 atmosphere) may be about 80° C. or less, in someembodiments about 70° C. or less, and in some embodiments, from about 0°C. to about 60° C. One example of such a compound is 2-methyl-1-propene.Contrary to conventional thought, the present inventors have discoveredthat the resulting composition can exhibit low volatile emissionsthrough selective control over the nature of the materials employed inthe polymer composition and the particular manner in which they arecombined together. For example, the fiber-reinforced composition mayexhibit a total volatile content (“VOC”) of about 100 microgramsequivalent carbon per gram of the composition (“μgC/g”) or less, in someembodiments about 70 μg/g or less, in some embodiments about 50 μg/g orless, and in some embodiments, about 40 μg/g or less, as determined inaccordance with VDA 277:1995. The composition may also exhibit a tolueneequivalent volatile content (“TVOC”) of about 250 micrograms equivalenttoluene per gram of the composition (“μg/g”) or less, in someembodiments about 150 μg/g or less, and in some embodiments, about 100μg/g or less, as well as a fogging content (“FOG”) of about 500micrograms hexadecane per gram of the composition (“μg/g”) or less, insome embodiments about 350 μg/g or less, and in some embodiments, about300 μg/g or less, each of which may be determined in accordance with VDA278:2002.

Despite having such a high degree of fluidity and low emission content,a part formed from the composition may still exhibit excellentmechanical properties. For example, the part may exhibit a Charpyunnotched impact strength greater than about 15 kJ/m², in someembodiments from about 20 to about 80 kJ/m², and in some embodiments,from about 30 to about 60 kJ/m², measured at according to ISO Test No.179-1:2010) (technically equivalent to ASTM D256-10e1) at varioustemperatures, such as −30° C., 23° C., or 80° C. The tensile andflexural mechanical properties may also be good. For example, the partsformed from the composition may exhibit a tensile strength of from about20 to about 300 MPa, in some embodiments from about 30 to about 200 MPa,and in some embodiments, from about 40 to about 150 MPa; a tensile breakstrain of about 0.5% or more, in some embodiments from about 0.6% toabout 5%, and in some embodiments, from about 0.7% to about 2.5%; and/ora tensile modulus of from about 3,500 MPa to about 20,000 MPa, in someembodiments from about 4,000 MPa to about 15,000 MPa, and in someembodiments, from about 5,000 MPa to about 10,000 MPa. The tensileproperties may be determined in accordance with ISO Test No. 527-1:2012(technically equivalent to ASTM D638-14) at −30° C., 23° C., or 80° C.Parts formed from the fiber-reinforced composition may also exhibit aflexural strength of from about 50 to about 500 MPa, in some embodimentsfrom about 80 to about 400 MPa, and in some embodiments, from about 100to about 250 MPa and/or a flexural modulus of from about 2000 MPa toabout 20,000 MPa, in some embodiments from about 3,000 MPa to about15,000 MPa, and in some embodiments, from about 4,000 MPa to about10,000 MPa. The flexural properties may be determined in accordance withISO Test No. 178:2010 (technically equivalent to ASTM D790-15e2) at −30°C., 23° C., or 80° C.

The present inventors have also discovered that the fiber-reinforcedcomposition is not highly sensitive to aging at high temperatures. Forexample, a part formed from the fiber-reinforced composition may be agedin an atmosphere having a temperature of from about 100° C. or more, insome embodiments from about 120° C. to about 200° C., and in someembodiments, from about 130° C. to about 180° C. (e.g., 150° C.) for atime period of about 100 hours or more, in some embodiments from about300 hours to about 3000 hours, and in some embodiments, from about 400hours to about 2500 hours (e.g., about 1,000 hours). Even after aging,the mechanical properties (e.g., impact strength, tensile properties,and/or flexural properties) may remain within the ranges noted above.For example, the ratio of a particular mechanical property (e.g., Charpyunnotched impact strength, flexural strength, etc.) after “aging” at150° C. for 1,000 hours to the initial mechanical property prior to suchaging may be about 0.6 or more, in some embodiments about 0.7 or more,and in some embodiments, from about 0.8 to 1.0. In one embodiment, forexample, a thin part (e.g., 1.2 mm in thickness) may exhibit a Charpyunnotched impact strength after being aged at a high temperature (e.g.,150° C.) for 1,000 hours of greater than about 15 kJ/m², in someembodiments from about 20 to about 80 kJ/m², and in some embodiments,from about 30 to about 60 kJ/m², measured according to ISO Test No.179-1:2010 at a temperature of 23° C.) (technically equivalent to ASTMD256-10e1). The thin part (e.g., 1.2 mm in thickness) may also, forexample, exhibit a flexural strength after being aged at a hightemperature atmosphere (e.g., 150° C.) for 1,000 hours of about 50 toabout 500 MPa, in some embodiments from about 80 to about 400 MPa, andin some embodiments, from about 100 to about 250 MPa, measured accordingto ISO Test No. 178:2010 at a temperature of 23° C. (technicallyequivalent to ASTM D790-15e2). Likewise, the thin part (e.g., 1.2 mm inthickness) may also exhibit a tensile strength after being aged at ahigh temperature atmosphere (e.g., 150° C.) for 1,000 hours of fromabout 20 to about 300 MPa, in some embodiments from about 30 to about200 MPa, and in some embodiments, from about 40 to about 150 MPa asdetermined at a temperature of 23° C. in accordance with ISO Test No.527-1:2012 (technically equivalent to ASTM D638-14).

The ability to achieve enhanced mechanical properties is due in part tothe high fiber length that can be retained in the composition after itis formed. Without intending to be limited by theory, it is believedthat the low viscosity of the polymer matrix can minimize the degree towhich the long fibers are abraded during extrusion and processing,thereby maximizing the overall length of the fibers. Thus, for example,the median length (the value of the fiber length at 50% in thecumulative distribution curve, also known as “D50”) of the fibers in thecomposition is typically about 1 millimeter or more, in some embodimentsabout 1.5 millimeters or more, in some embodiments about 2.0 millimetersor more, and in some embodiments, from about 2.5 to about 8 millimeters.

In light of the properties discussed above, such as high fluidity, lowemissions, and good mechanical strength and flexibility, the presentinventors have discovered that the fiber-reinforced composition isparticularly suitable for use in interior and exterior automotive parts(e.g., injection molded parts). Suitable exterior automotive parts mayinclude fan shrouds, sunroof systems, door panels, front end modules,side body panels, underbody shields, bumper panels, cladding (e.g., nearthe rear door license plate), cowls, spray nozzle body, capturing hoseassembly, pillar cover, rocker panel, etc. Likewise, suitable interiorautomotive parts that may be formed from the fiber-reinforcedcomposition of the present invention may include, for instance, pedalmodules, instrument panels (e.g., dashboards), arm rests, consoles(e.g., center consoles), seat structures (e.g., backrest of the rearbench or seat covers), interior modules (e.g., trim, body panel, or doormodule), lift gates, interior organizers, step assists, ash trays, gloveboxes, gear shift levers, etc. Referring to FIG. 3, for example, oneembodiment of an automotive interior 1000 is shown having an interiordoor module 100 a and an instrument panel 100 b, one or both of whichmay be formed entirely or in part from the fiber-reinforced polymercomposition of the present invention. FIG. 4, for example, depicts aparticular embodiment of the interior automotive module 100 a thatincludes an arm rest component 110 a, first padded component 110 b,second padded component 110 c, and trim component 110 d. The door module100 a can also include a base component 120 a and an accent component120 b. The base component 120 a may be formed around each of thecomponents of the automotive module 100 a.

Various embodiments of the present invention will now be described inmore detail.

I. Polymer Matrix

Any of a variety of propylene polymers or combinations of propylenepolymers may generally be employed in the polymer matrix, such aspropylene homopolymers (e.g., syndiotactic, atactic, isotactic, etc.),propylene copolymers, and so forth. In one embodiment, for instance, apropylene polymer may be employed that is an isotactic or syndiotactichomopolymer. The term “syndiotactic” generally refers to a tacticity inwhich a substantial portion, if not all, of the methyl groups alternateon opposite sides along the polymer chain. On the other hand, the term“isotactic” generally refers to a tacticity in which a substantialportion, if not all, of the methyl groups are on the same side along thepolymer chain. Such homopolymers may have a melting point of from about160° C. to about 170° C. In yet other embodiments, a copolymer ofpropylene with an α-olefin monomer may be employed. Specific examples ofsuitable α-olefin monomers may include ethylene, 1-butene;3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with oneor more methyl, ethyl or propyl substituents; 1-hexene with one or moremethyl, ethyl or propyl substituents; 1-heptene with one or more methyl,ethyl or propyl substituents; 1-octene with one or more methyl, ethyl orpropyl substituents; 1-nonene with one or more methyl, ethyl or propylsubstituents; ethyl, methyl or dimethyl-substituted 1-decene;1-dodecene; and styrene. The propylene content of such copolymers may befrom about 60 mole % to about 99 mole %, in some embodiments from about80 mole % to about 98.5 mole %, and in some embodiments, from about 87mole % to about 97.5 mole %. The α-olefin content may likewise rangefrom about 1 mole % to about 40 mole %, in some embodiments from about1.5 mole % to about 15 mole %, and in some embodiments, from about 2.5mole % to about 13 mole %.

Any of a variety of known techniques may generally be employed to formthe propylene homopolymers and propylene/α-olefin copolymers. Forinstance, olefin polymers may be formed using a free radical or acoordination catalyst (e.g., Ziegler-Natta). Typically, however, thecopolymer is formed from a single-site coordination catalyst, such as ametallocene catalyst, to help minimize the degree of volatile organicemissions. Such a catalyst system produces copolymers in which thecomonomer is randomly distributed within a molecular chain and uniformlydistributed across the different molecular weight fractions. Examples ofmetallocene catalysts include bis(n-butylcyclopentadienyl)titaniumdichloride, bis(n-butylcyclopentadienyl)zirconium dichloride,bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconiumdichloride, bis(methylcyclopentadienyl)titanium dichloride,bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene,cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride,isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride,molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene,titanocene dichloride, zirconocene chloride hydride, zirconocenedichloride, and so forth. Polymers made using metallocene catalyststypically have a narrow molecular weight range. For instance,metallocene-catalyzed polymers may have polydispersity numbers (Mw/Mn)of below 4, controlled short chain branching distribution, andcontrolled isotacticity.

It should be noted that the polymer matrix may contain a propylenepolymer in combination with one or more additional polymers, which mayor may not themselves be propylene polymers. In some embodiments, forinstance, a blend of propylene polymers may be employed, such as a blendof a propylene homopolymer and a propylene/α-olefin copolymer, blend ofmultiple propylene homopolymers, or a blend of multiplepropylene/α-olefin copolymers. In one particular embodiment, forinstance, the polymer matrix contains at least one propylenehomopolymer, which is typically metallocene-catalyzed. In suchembodiments, the polymer matrix may contain only propylene homopolymers.Alternatively, the polymer matrix may contain a blend of a propylenehomopolymer (e.g., metallocene-catalyzed) and a propylene/α-olefincopolymer, which may be metallocene-catalyzed or formed from other typesof processes (e.g., Ziegler Natta-catalyzed). In one embodiment, a blendmay be employed that contains propylene homopolymers in an amount offrom about 30 wt. % to about 70 wt. %, in some embodiments from about 35wt. % to about 65 wt. %, and in some embodiments, from about 40 wt. % toabout 60 wt. % of the matrix, and propylene α-olefin copolymers in anamount of from about 30 wt. % to about 70 wt. %, in some embodimentsfrom about 35 wt. % to about 65 wt. %, and in some embodiments, fromabout 40 wt. % to about 60 wt. % of the matrix.

Regardless of the polymers employed, the high flow composition istypically achieved by melt blending at least one relatively highviscosity propylene polymer with a chain-scission agent. Thechain-scission agent may, for instance, be a free radical-generatingfunctional compound, such as an organic peroxide, which can result inbeta chain scission of the polymer backbone during the melt extrusionprocess. Among other things, this can reduce the molecular weight andmelt viscosity of the polymer under shear to result in a “high flow”propylene polymer. Particularly suitable compounds for this purpose mayinclude, for instance, persulfates, azonitroles (e.g.,azobisisopropionitrile and azobisisobutyronitrile), peroxides (e.g.,hydrogen peroxide, inorganic peroxides, organic peroxides, etc.), etc.,as well as mixtures thereof. In one particular embodiment, for instance,an organic peroxide may be employed in the composition. Suitable organicperoxides may include those of the aliphatic hydrocarbon, aromatichydrocarbon, carboxylic acid ester, ketone, or carbonic acid estertypes, and specific examples include diisopropyl peroxide, ditertiarybutyl peroxide, tertiary butyl hydroperoxide, dicumyl peroxide,dibenzoyl peroxide, cumyl hydroperoxide, tertiary butyl peracetate,tertiary butyl peroxy laurate, tertiary butyl perbenzoate, ditertiarybutyl perphthalate, methylethylketone peroxide, octanol peroxide, anddiisopropyl peroxycarbonate. Although the amount may vary, it istypically desired that the chain-scission agent is present in an amountof from about 0.001 wt. % to about 0.5 wt. %, in some embodiments fromabout 0.005 wt. % to about 0.1 wt %, and in some embodiments, from about0.01 wt. % to 0.06 wt. %, based on weight of the propylene polymer.

During the melt blending process, the raw materials (e.g., propylenepolymer, chain-scission agent, etc.) may be supplied eithersimultaneously or in sequence to a melt-blending device thatdispersively blends the materials. Batch and/or continuous melt blendingtechniques may be employed. For example, a mixer/kneader, Banbury mixer,Farrel continuous mixer, single-screw extruder, twin-screw extruder,roll mill, etc., may be utilized to blend the materials. Oneparticularly suitable melt-blending device is a co-rotating, twin-screwextruder (e.g., ZSK-30 twin-screw extruder available from Werner &Pfleiderer Corporation of Ramsey, N.J.). Such extruders may includefeeding and venting ports and provide high intensity distributive anddispersive mixing, which facilitate the chain scission reaction. Forexample, the propylene polymer may be fed to a feeding port of thetwin-screw extruder and melted. Thereafter, the chain-scission agent maybe injected into the polymer melt. Alternatively, the chain-scissionagent may be separately fed into the extruder at a different point alongits length. Regardless of the particular melt blending technique chosen,the raw materials are blended under high shear/pressure and heat toensure sufficient mixing for initiating the chain scission reaction. Forexample, melt blending may occur at a temperature of from about 150° C.to about 300° C., in some embodiments, from about 155° C. to about 250°C., and in some embodiments, from about 160° C. to about 220° C. Themelt flow index of the “high flow” propylene polymer to the melt flowindex of the neat propylene polymer prior to combination with thechain-scission agent is typically about 1.1 or more, in some embodimentsabout 1.2 or more, in some embodiments from about 1.3 to about 4.0, andin some embodiments, from about 1.4 to about 3.0. The neat propylenepolymer may, for instance, have a relatively low melt flow index, suchas about 200 grams per 10 minutes or less, in some embodiments about 180grams per 10 minutes or less, and in some embodiments, from about 50 toabout 150 grams per 10 minutes, as determined in accordance with ISO1133-1:2011 (technically equivalent to ASTM D1238-13) at a load of 2.16kg and temperature of 230° C.

As noted above, certain embodiments of the present invention contemplatethe use of a blend of polymers within the polymer matrix (e.g.,propylene homopolymers and/or propylene/α-olefin copolymers). In suchembodiments, each of the polymers employed in the blend may be meltblended with the chain-scission agent to reduce melt viscosity in themanner described above. In yet other embodiments, however, it may bedesired to melt blend a first propylene polymer (e.g., homopolymer orcopolymer) with the chain-scission agent to form a concentrate, which isthen reinforced with long fibers in the manner described below to form aprecursor composition. The precursor composition may thereafter beblended (e.g., dry blended) with a second propylene polymer to form afiber-reinforced composition with the desired melt flow properties.Notably, in such embodiments, the second propylene polymer does notappreciably react with the chain-scission agent and thus effectivelyacts as a viscosity enhancer such that the melt flow index of theprecursor polymer matrix is actually lower than the melt flow index ofthe final blended polymer matrix. It should also be understood thatadditional polymers can also be added during prior to and/or duringreinforcement of the polymer matrix with the long fibers.

II. Long Fibers

To form the fiber-reinforced composition of the present invention, longfibers are generally embedded within the polymer matrix. The term “longfibers” generally refers to fibers, filaments, yarns, or rovings (e.g.,bundles of fibers) that are not continuous and have a length of fromabout 1 to about 25 millimeters, in some embodiments, from about 1.5 toabout 20 millimeters, in some embodiments from about 2 to about 15millimeters, and in some embodiments, from about 3 to about 12millimeters. As noted above, due to the unique properties of thecomposition, a substantial portion of the fibers may maintain arelatively large length even after being formed into a shaped part(e.g., injection molding). That is, the median length (D50) of thefibers in the composition may be about 1 millimeter or more, in someembodiments about 1.5 millimeters or more, in some embodiments about 2.0millimeters or more, and in some embodiments, from about 2.5 to about 8millimeters.

The fibers may be formed from any conventional material known in theart, such as metal fibers; glass fibers (e.g., E-glass, A-glass,C-glass, D-glass, AR-glass, R-glass, S1-glass, S2-glass), carbon fibers(e.g., graphite), boron fibers, ceramic fibers (e.g., alumina orsilica), aramid fibers (e.g., Kevlar®), synthetic organic fibers (e.g.,polyamide, polyethylene, paraphenylene, terephthalamide, polyethyleneterephthalate and polyphenylene sulfide), and various other natural orsynthetic inorganic or organic fibrous materials known for reinforcingthermoplastic compositions. Glass fibers and carbon fibers areparticularly desirable. Such fibers often have a nominal diameter ofabout 4 to about 35 micrometers, and in some embodiments, from about 9to about 35 micrometers. The fibers may be twisted or straight. Ifdesired, the fibers may be in the form of rovings (e.g., bundle offibers) that contain a single fiber type or different types of fibers.Different fibers may be contained in individual rovings or,alternatively, each roving may contain a different fiber type. Forexample, in one embodiment, certain rovings may contain carbon fibers,while other rovings may contain glass fibers. The number of fiberscontained in each roving can be constant or vary from roving to roving.Typically, a roving may contain from about 1,000 fibers to about 50,000individual fibers, and in some embodiments, from about 2,000 to about40,000 fibers.

III. Technique for Forming the Fiber-Reinforced Composition

Any of a variety of different techniques may generally be employed toincorporate the fibers into the polymer matrix. The long fibers may berandomly distributed within the polymer matrix, or alternativelydistributed in an aligned fashion. In one embodiment, for instance,continuous fibers may initially be impregnated into the polymer matrixto form strands, which are thereafter cooled and then chopped intopellets to that the resulting fibers have the desired length for thelong fibers. In such embodiments, the polymer matrix and continuousfibers (e.g., rovings) are typically pultruded through an impregnationdie to achieve the desired contact between the fibers and the polymer.Pultrusion can also help ensure that the fibers are spaced apart andoriented in a longitudinal direction that is parallel to a major axis ofthe pellet (e.g., length), which further enhances the mechanicalproperties. Referring to FIG. 1, for instance, one embodiment of apultrusion process 10 is shown in which a polymer matrix is suppliedfrom an extruder 13 to an impregnation die 11 while continuous fibers 12are a pulled through the die 11 via a puller device 18 to produce acomposite structure 14. Typical puller devices may include, for example,caterpillar pullers and reciprocating pullers. While optional, thecomposite structure 14 may also be pulled through a coating die 15 thatis attached to an extruder 16 through which a coating resin is appliedto form a coated structure 17. As shown in FIG. 1, the coated structure17 is then pulled through the puller assembly 18 and supplied to apelletizer 19 that cuts the structure 17 into the desired size forforming the long fiber-reinforced composition.

The nature of the impregnation die employed during the pultrusionprocess may be selectively varied to help achieved good contact betweenthe polymer matrix and the long fibers. Examples of suitableimpregnation die systems are described in detail in Reissue patent No.32,772 to Hawley; U.S. Pat. No. 9,233,486 to Regan, et al.; and U.S.Pat. No. 9,278,472 to Eastep, et al. Referring to FIG. 2, for instance,one embodiment of such a suitable impregnation die 11 is shown. Asshown, a polymer matrix 127, which may contain the reaction product ofthe propylene polymer and chain-scission agent, may be supplied to theimpregnation die 11 via an extruder (not shown). More particularly, thepolymer matrix 127 may exit the extruder through a barrel flange 128 andenter a die flange 132 of the die 11. The die 11 contains an upper diehalf 134 that mates with a lower die half 136. Continuous fibers 142(e.g., roving) are supplied from a reel 144 through feed port 138 to theupper die half 134 of the die 11. Similarly, continuous fibers 146 arealso supplied from a reel 148 through a feed port 140. The matrix 127 isheated inside die halves 134 and 136 by heaters 133 mounted in the upperdie half 134 and/or lower die half 136. The die is generally operated attemperatures that are sufficient to cause melting and impregnation ofthe thermoplastic polymer. Typically, the operation temperatures of thedie is higher than the melt temperature of the polymer matrix. Whenprocessed in this manner, the continuous fibers 142 and 146 becomeembedded in the matrix 127. The mixture is then pulled through theimpregnation die 11 to create a fiber-reinforced composition 152. Ifdesired, a pressure sensor 137 may also sense the pressure near theimpregnation die 11 to allow control to be exerted over the rate ofextrusion by controlling the rotational speed of the screw shaft, or thefederate of the feeder.

Within the impregnation die, it is generally desired that the fiberscontact a series of impingement zones. At these zones, the polymer meltmay flow transversely through the fibers to create shear and pressure,which significantly enhances the degree of impregnation. This isparticularly useful when forming a composite from ribbons of a highfiber content. Typically, the die will contain at least 2, in someembodiments at least 3, and in some embodiments, from 4 to 50impingement zones per roving to create a sufficient degree of shear andpressure. Although their particular form may vary, the impingement zonestypically possess a curved surface, such as a curved lobe, rod, etc. Theimpingement zones are also typically made of a metal material.

FIG. 2 shows an enlarged schematic view of a portion of the impregnationdie 11 containing multiple impingement zones in the form of lobes 182.It should be understood that this invention can be practiced using aplurality of feed ports, which may optionally be coaxial with themachine direction. The number of feed ports used may vary with thenumber of fibers to be treated in the die at one time and the feed portsmay be mounted in the upper die half 134 or the lower die half 136. Thefeed port 138 includes a sleeve 170 mounted in upper die half 134. Thefeed port 138 is slidably mounted in a sleeve 170. The feed port 138 issplit into at least two pieces, shown as pieces 172 and 174. The feedport 138 has a bore 176 passing longitudinally therethrough. The bore176 may be shaped as a right cylindrical cone opening away from theupper die half 134. The fibers 142 pass through the bore 176 and enter apassage 180 between the upper die half 134 and lower die half 136. Aseries of lobes 182 are also formed in the upper die half 134 and lowerdie half 136 such that the passage 210 takes a convoluted route. Thelobes 182 cause the fibers 142 and 146 to pass over at least one lobe sothat the polymer matrix inside the passage 180 thoroughly contacts eachof the fibers. In this manner, thorough contact between the moltenpolymer and the fibers 142 and 146 is assured.

To further facilitate impregnation, the fibers may also be kept undertension while present within the impregnation die. The tension may, forexample, range from about 5 to about 300 Newtons, in some embodimentsfrom about 50 to about 250 Newtons, and in some embodiments, from about100 to about 200 Newtons per tow of fibers. Furthermore, the fibers mayalso pass impingement zones in a tortuous path to enhance shear. Forexample, in the embodiment shown in FIG. 2, the fibers traverse over theimpingement zones in a sinusoidal-type pathway. The angle at which therovings traverse from one impingement zone to another is generally highenough to enhance shear, but not so high to cause excessive forces thatwill break the fibers. Thus, for example, the angle may range from about1° to about 30°, and in some embodiments, from about 5° to about 25°.

The impregnation die shown and described above is but one of variouspossible configurations that may be employed in the present invention.In alternative embodiments, for example, the fibers may be introducedinto a crosshead die that is positioned at an angle relative to thedirection of flow of the polymer melt. As the fibers move through thecrosshead die and reach the point where the polymer exits from anextruder barrel, the polymer is forced into contact with the fibers. Itshould also be understood that any other extruder design may also beemployed, such as a twin screw extruder. Still further, other componentsmay also be optionally employed to assist in the impregnation of thefibers. For example, a “gas jet” assembly may be employed in certainembodiments to help uniformly spread a bundle or tow of individualfibers, which may each contain up to as many as 24,000 fibers, acrossthe entire width of the merged tow. This helps achieve uniformdistribution of strength properties in the ribbon. Such an assembly mayinclude a supply of compressed air or another gas that impinges in agenerally perpendicular fashion on the moving fiber tows that passacross the exit ports. The spread fiber bundles may then be introducedinto a die for impregnation, such as described above.

The fiber-reinforced composition may generally be employed to form ashaped part using a variety of different techniques. Suitable techniquesmay include, for instance, injection molding, low-pressure injectionmolding, extrusion compression molding, gas injection molding, foaminjection molding, low-pressure gas injection molding, low-pressure foaminjection molding, gas extrusion compression molding, foam extrusioncompression molding, extrusion molding, foam extrusion molding,compression molding, foam compression molding, gas compression molding,etc. For example, an injection molding system may be employed thatincludes a mold within which the fiber-reinforced composition may beinjected. The time inside the injector may be controlled and optimizedso that polymer matrix is not pre-solidified. When the cycle time isreached and the barrel is full for discharge, a piston may be used toinject the composition to the mold cavity. Compression molding systemsmay also be employed. As with injection molding, the shaping of thefiber-reinforced composition into the desired article also occurs withina mold. The composition may be placed into the compression mold usingany known technique, such as by being picked up by an automated robotarm. The temperature of the mold may be maintained at or above thesolidification temperature of the polymer matrix for a desired timeperiod to allow for solidification. The molded product may then besolidified by bringing it to a temperature below that of the meltingtemperature. The resulting product may be de-molded. The cycle time foreach molding process may be adjusted to suit the polymer matrix, toachieve sufficient bonding, and to enhance overall process productivity.

The present invention may be better understood with reference to thefollowing examples.

Test Methods

Melt Flow Index: The melt flow index of a polymer or polymer compositionmay be determined in accordance with ISO 1133-1:2011 (technicallyequivalent to ASTM D1238-13) at a load of 2.16 kg and temperature of230° C.

Spiral Flow Length: The term “spiral flow length” generally refers tothe length reached by the flow of the composition in a spiral flowchannel when it is injected at constant injection temperature andinjection pressure from a central gate of a mold in which the spiralflow channel is formed. The spiral flow length may be determined inaccordance with ASTM D3123-09 at a barrel temperature of 230° C.,molding temperature of 40° C. to 60° C., and a maximum injectionpressure of 860 bar.

Volatile Organic Content (“VOC”): The total volatile organic content maybe determined in accordance with an automotive industry standard testknown as VDA 277:1995. In this test, for instance, a gas chromatography(GC) device may be employed with a WCOT-capillary column (wax type) of0.25 mm inner diameter and 30 m length. The GC settings may be asfollows: 3 minutes isothermal at 50° C., heat up to 200° C. at 12 K/min,4 minutes isothermal at 200° C., injection-temperature of 200° C.,detection-temperature of 250° C., carrier is helium, flow-mode split of1:20 and average carrier-speed of 22-27 cm/s. A flame ionizationdetector (“FID”) may be employed to determine the total volatile contentand a mass spectrometry (“MS”) detector may also be optionally employedto determine single volatile components. After testing, the VOC amountis calculated by dividing the amount of volatiles (micrograms of carbonequivalents) by the weight (grams) of the composition.

Toluene Volatile Organic Content (“TVOC”): The toluene-equivalentvolatile organic content may be determined in accordance with anautomotive industry standard test known as VDA 278:2002. Moreparticularly, measurements may be made on a sample using athermaldesoprtion analyzer (“TDSA”), such as supplied by Gerstel usinghelium 5.0 as carrier gas and a column HP Ultra 2 of 50 m length and0.32 mm diameter and 0.52 μm coating of 5% phenylmethylsiloxane. Theanalysis may, for example, be performed using device setting 1 and thefollowing parameters: flow mode of splitless, final temperature of 90°C.; final time of 30 min, and rate of 60 K/min. The cooling trap may bepurged with a flow-mode split of 1:30 in a temperature range from −150°C. to +280° C. with a heating rate of 12 K/sec and a final time of 5min. For analysis, the gas chromatography (“GC”) settings may be 2 minisothermal at 40° C., heating at 3 K/min up to 92° C., then at 5 K/minup to 160° C., and then at 10 K/min up to 280° C., 10 minutesisothermal, and flow of 1.3 ml/min. After testing, the TVOC amount iscalculated by dividing the amount of volatiles (micrograms of tolueneequivalents) by the weight (grams) of the composition.

Fogging Content (“FOG”): The fogging content may be determined inaccordance with an automotive industry standard test known as VDA278:2002. More particularly, measurements may be made on a sample usinga thermaldesoprtion analyzer (“TDSA”), such as supplied by Gerstel usinghelium 5.0 as carrier gas and a column HP Ultra 2 of 50 m length and0.32 mm diameter and 0.52 μm coating of 5% phenylmethylsiloxane. Theanalysis may, for example, be performed using device setting 1 and thefollowing parameters: flow mode of splitless, final temperature of 120°C.; final time of 60 min, and rate of 60 K/min. The cooling trap may bepurged with a flow-mode split of 1:30 in a temperature range from −150°C. to +280° C. with a heating rate of 12 K/sec. For analysis, the gaschromatography (“GC”) settings may be 2 min isothermal at 50° C.,heating at 25 K/min up to 160° C., then at 10 K/min up to 280° C., 30minutes isothermal, and flow of 1.3 ml/min. After testing, the FOGamount is calculated by dividing the amount of volatiles (micrograms ofhexadecane equivalents) by the weight (grams) of the composition.

Tensile Modulus, Tensile Stress, and Tensile Elongation at Break:Tensile properties may be tested according to ISO Test No. 527-1:2012(technically equivalent to ASTM D638-14). Modulus and strengthmeasurements may be made on a dogbone-shaped test strip sample having alength of 170/190 mm, thickness of 4 mm, and width of 10 mm. The testingtemperature may be −30° C., 23° C., or 80° C. and the testing speeds maybe 1 or 5 mm/min.

Flexural Modulus, Flexural Elongation at Break, and Flexural Stress:Flexural properties may be tested according to ISO Test No. 178:2010(technically equivalent to ASTM D790-15e2). This test may be performedon a 64 mm support span. Tests may be run on the center portions ofuncut ISO 3167 multi-purpose bars. The testing temperature may be −30°C., 23° C., or 80° C. and the testing speed may be 2 mm/min.

Unotched and Notched Charpy Impact Strength: Charpy properties may betested according to ISO Test No. ISO 179-1:2010) (technically equivalentto ASTM D256-10, Method B). This test may be run using a Type 1 specimensize (length of 80 mm, width of 10 mm, and thickness of 4 mm). Whentesting the notched impact strength, the notch may be a Type A notch(0.25 mm base radius). Specimens may be cut from the center of amulti-purpose bar using a single tooth milling machine. The testingtemperature may be −30° C., 23° C., or 80° C.

Deflection Temperature Under Load (“DTUL”): The deflection under loadtemperature may be determined in accordance with ISO Test No. 75-2:2013(technically equivalent to ASTM D648-07). More particularly, a teststrip sample having a length of 80 mm, width of 10 mm, and thickness of4 mm may be subjected to an edgewise three-point bending test in whichthe specified load (maximum outer fibers stress) was 1.8 Megapascals.The specimen may be lowered into a silicone oil bath where thetemperature is raised at 2° C. per minute until it deflects 0.25 mm(0.32 mm for ISO Test No. 75-2:2013).

Example 1

A sample is formed that contains approximately 33.3 wt. % of ametallocene-catalyzed propylene homopolymer (melt flow index of 140 g/10min, density of 0.905 g/cm³), 0.9 wt. % of a peroxide, 2 wt. % of acoupling agent, 0.6 wt. % of a black pigment, 3.2 wt. % stabilizers, and60 wt. % continuous glass fiber rovings (2400 Tex, filament diameter of16 μm). The sample is melt processed in a single screw extruder (90 mm)in which the melt temperature is 265° C., the die temperature is 330°C., and the zone temperatures range from 160° C. to 320° C., and thescrew speed is 160 rpm. The melt flow index of the resulting sample is500 g/10 min and the median length of the glass fibers (“D50”) is 3.171mm.

Example 2

A sample is formed as described in Example 1 and then blended down witha metallocene-catalyzed propylene homopolymer (melt flow index of 140g/10 min, density of 0.905 g/cm³) so that the glass fiber rovings arepresent in an amount of about 20 wt. %. The melt flow index of theresulting sample is 230 g/10 min.

Example 3

A sample is formed as described in Example 1 and then blended down witha metallocene-catalyzed propylene homopolymer (melt flow index of 140g/10 min, density of 0.905 g/cm³) so that the glass fiber rovings arepresent in an amount of about 30 wt. %. The melt flow index of theresulting sample is 260 g/10 min.

Example 4

A sample is formed as described in Example 1 and then blended down witha metallocene-catalyzed propylene homopolymer (melt flow index of 140g/10 min, density of 0.905 g/cm³) so that the glass fiber rovings arepresent in an amount of about 40 wt. %. The melt flow index of theresulting sample is 300 g/10 min.

Molded specimens having a thickness of 1.2 mm, 1.6 mm, and 4 mm may beformed from the samples of Examples 1-4 using the following processconditions: nozzle temperature of 250° C., injection pressure of 1025bar, back pressure of 650 bar, injection speed of 16.6 millimeters persecond, and molding temperature of 40° C. Parts having a thickness of1.2 mm and 4 mm are tested at 23° C. and then after heat aging at 150°C. for 1,000 hours. The results are set forth below in Tables 1-2.

TABLE 1 Properties for Parts Having a Thickness of 4 mm Units Example 1Example 2 Example 3 Example 4 Tensile modulus MPa 14781 4970 7494 9436(1 mm/min) 23° C. Tensile modulus 80° C. MPa 10326 — — — Tensilestrength 23° C. MPa 145 96 125 138 Tensile strength 80° C. MPa 84.8Tensile strain @ break % 1.43 2.52 2.19 2.02 (5 mm/min) 23° C. Tensilestrain @ break % 1.51 — — — (5 mm/min) 80° C. Flexural modulus 23° C.MPa 16332 4917 7011 9062 Flexural modulus 80° C. MPa 11127 2969 43095424 Flexural strength 23° C. MPa 246 135 176 207 Flexural strength 80°C. MPa 146 98 125 139 Flexural strain 23° C. % 2.07 3.24 3.05 2.85Flexural strain 80° C. % 2.6 3.67 3.32 3.14 Unnotched Charpy kJ/m² 64 4659 68 impact strength 23° C. Unnotched Charpy kJ/m² 80 25 41 55 impactstrength −30° C. Charpy notched kJ/m² 32 13 21 26 impact strength 23° C.Charpy notched kJ/m² 39 19 27 31 impact strength −30° C. DTUL ° C. 151151 152 152 Spiral Flow T = 2 mm 426 842 744 613

TABLE 2 Properties for Parts Having a Thickness of 1.2 mm Example 3 (23°C., after Example 3 aging Units (23° C.) at 150° C. Tensile modulus (lmm/min) MPa 6,379 6,630 Tensile strength MPa 87.1 59.7 Tensile strain @break % 1.76 1.04 (5 mm/min) Flexural modulus MPa 5,445 5,780 Flexuralstrength MPa 154 147 Unnotched Charpy impact kJ/m² 39.1 32.2 strengthSpiral Flow T = 2 mm 802 —

The organic volatile content of Examples 1-4 was also determined asdescribed herein, and the results are set forth in the table below.

Units Example 1 Example 2 Example 3 Example 4 VOC μgC/g 31 14 13 12 TVOCμg/g 213 43 46 92 FOG μg/g 337 128 132 212

Example 5

A sample is formed as described in Example 1 and then blended down witha propylene impact copolymer (melt flow index of 100 g/10 min) so thatthe glass fiber rovings are present in an amount of about 20 wt. %.

Example 6

A sample is formed as described in Example 1 and then blended down witha propylene impact copolymer (melt flow index of 100 g/10 min) so thatthe glass fiber rovings are present in an amount of about 30 wt. %.

Example 7

A sample is formed as described in Example 1 and then blended down witha propylene impact copolymer (melt flow index of 100 g/10 min) so thatthe glass fiber rovings are present in an amount of about 40 wt. %.

Molded specimens having a thickness of 4 mm may be formed from thesamples of Examples 5-7 using the following process conditions: nozzletemperature of 250° C., injection pressure of 1025 bar, back pressure of650 bar, injection speed of 16.6 millimeters per second, and moldingtemperature of 40° C. Parts having a thickness of 4 mm are tested at 23°C. The results are set forth below.

Example Example Example Units 5 6 7 Tensile modulus MPa 4,928 6,8409,086 (1 mm/min) 23° C. Tensile strength 23° C. MPa 87 110 131 Tensilestrain @ break % 2.39 2.16 2.03 (5 mm/min) 23° C. Flexural modulus 23°C. MPa 4,733 6,630 8,869 Flexural strength 23° C. MPa 124.6 161.0 190.4Flexural strain 23° C. % 3.15 3.00 2.74 Spiral Flow T = 2 mm 868 755 644

Example 8

A sample is formed that contains approximately 33.3 wt. % of a propyleneimpact copolymer (melt flow index of 100 g/10 min, 0.9 wt. % of aperoxide, 2 wt. % of a coupling agent, 0.6 wt. % of a black pigment, 3.2wt. % stabilizers, and 60 wt. % continuous glass fiber rovings (2400Tex, filament diameter of 16 μm). The sample is melt processed in asingle screw extruder (90 mm) in which the melt temperature is 265° C.,the die temperature is 330° C., and the zone temperatures range from160° C. to 320° C., and the screw speed is 160 rpm.

Example 9

A sample is formed as described in Example 8 and then blended down witha metallocene-catalyzed propylene homopolymer (melt flow index of 140g/10 min, density of 0.905 g/cm³) so that the glass fiber rovings arepresent in an amount of about 20 wt. %.

Example 10

A sample is formed as described in Example 8 and then blended down witha metallocene-catalyzed propylene homopolymer (melt flow index of 140g/10 min, density of 0.905 g/cm³) so that the glass fiber rovings arepresent in an amount of about 30 wt. %.

Molded specimens may be formed from the samples of Examples 9-10 usingthe following process conditions: nozzle temperature of 250° C.,injection pressure of 1025 bar, back pressure of 650 bar, injectionspeed of 16.6 millimeters per second, and molding temperature of 40° C.Parts having a thickness of 1.2 mm are tested for impact strength,spiral flow, and volatile content. The results are set forth below.

Units Example 9 Example 10 Unnotched Charpy Impact kJ/m² 32.6 57.4Strength at −30° C. Spiral Flow T = 2 mm 950 794 VOC μgC/g 34.3 50.2TVOC μg/g 64.1 108.3 FOG μg/g 192.8 196.6

Example 11

A sample is formed that contains approximately 74.8 wt. % of ametallocene-catalyzed propylene homopolymer (melt flow index of 32 g/10min, density of 0.90 g/cm³), 0.75 wt. % of a peroxide, 1.6 wt. % of acoupling agent, 1.2 wt. % of a black pigment, 2.3 wt. %stabilizers/additives, and 20 wt. % continuous glass fiber rovings. Thesample is melt processed in a twin screw extruder (26 mm) in which themelt temperature is 230° C., the die temperature is 250° C., and thezone temperatures range from 200° C. to 250° C., and the screw speed is250 rpm. The melt flow index of the resulting sample is 250 g/10 min.

Example 12

A sample is formed that contains approximately 74.9 wt. % of ametallocene-catalyzed propylene copolymer (melt flow index of 35 g/10min), 1.28 wt. % of a peroxide, 1.6 wt. % of a coupling agent, 1.2 wt. %of a black pigment, 2.2 wt. % stabilizers/additives, and 20 wt. %continuous glass fiber rovings. The sample is melt processed in a singlescrew extruder (90 mm) in which the melt temperature is 230° C., the dietemperature is 250° C., and the zone temperatures range from 200° C. to250° C., and the screw speed is 250 rpm. The melt flow index of theresulting sample is 250 g/10 min.

Example 13

A sample is formed that contains approximately 65.8 wt. % of ametallocene-catalyzed propylene homopolymer (melt flow index of 65 g/10min, density of 0.90 g/cm³), 0.66 wt. % of a peroxide, 1.4 wt. % of acoupling agent, 1.1 wt. % of a black pigment, 1.7 wt. %stabilizers/additives, and 30 wt. % continuous glass fiber rovings. Thesample is melt processed in a single screw extruder (90 mm) in which themelt temperature is 230° C., the die temperature is 250° C., and thezone temperatures range from 200° C. to 250° C., and the screw speed is250 rpm. The melt flow index of the resulting sample is 250 g/10.

Example 14

A sample is formed that contains approximately 65.5 wt. % of ametallocene-catalyzed propylene copolymer (melt flow index of 35 g/10min), 1.12 wt. % of a peroxide, 1.4 wt. % of a coupling agent, 1.1 wt. %of a black pigment, 2.0 wt. % stabilizers/additives, and 30 wt. %continuous glass fiber rovings. The sample is melt processed in a singlescrew extruder (90 mm) in which the melt temperature is 230° C., the dietemperature is 250° C., and the zone temperatures range from 200° C. to250° C., and the screw speed is 250 rpm. The melt flow index of theresulting sample is 250 g/10 min.

Molded specimens may be formed from the samples of Examples 11-14 usingthe following process conditions: nozzle temperature of 250° C.,injection pressure of 1025 bar, back pressure of 650 bar, injectionspeed of 16.6 millimeters per second, and molding temperature of 40° C.Parts having a thickness of 4 mm are tested for tensile properties,flexural properties, impact strength, spiral flow, and volatile content.The results are set forth below.

Example Example Example Example Units 11 12 13 14 Tensile Modulus (1mm/min) 23° C. MPa 4,507 4,693 6,635 5,867 Tensile Modulus (1 mm/min)23° C., MPa 5,244 5,179 7,227 6,293 after aging at 150° C. for 1000 hrsTensile strength 23° C., after aging MPa 86.7 80.2 100.6 168.2 at 150°C. for 1000 hrs Tensile Strength 150° C., 1000 hrs MPa 64 61 76 82Flexural Modulus 23° C. MPa 4,578 4,586 6,371 5,995 Flexural Strength23° C. MPa 150.3 141.1 177.7 168.2 Notched Impact Strength 23° C. kJ/m²14.04 51.22 22.83 63.05 Spiral Flow T = 2 mm 1,213 1,108 1,148 1,009 VOCμgC/g 2.76 16.58 — — FOG μg/g 20.15 27.12 — —

These and other modifications and variations of the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present invention. Inaddition, it should be understood that aspects of the variousembodiments may be interchanged both in whole or in part. Furthermore,those of ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to limit theinvention so further described in such appended claims.

1. A fiber-reinforced polymer composition comprising: a polymer matrixthat contains a propylene polymer, wherein the polymer matrixconstitutes from about 30 wt. % to about 90 wt. % of the composition;and a plurality of long reinforcing fibers that are distributed withinthe polymer matrix, wherein the fibers constitute from about 10 wt. % toabout 70 wt. % of the composition, wherein the polymer compositionexhibits a spiral flow length of about 450 millimeters or more asdetermined in accordance with ASTM D3123-09, and further wherein thecomposition exhibits a volatile organic content of about 100 μgC/g orless as determined in accordance with VDA 277:1995.
 2. Thefiber-reinforced polymer composition of claim 1, wherein the compositionexhibits a toluene equivalent volatile organic content of about 250 μg/gor less as determined in accordance with VDA 278:2002.
 3. Thefiber-reinforced polymer composition of claim 1, wherein the compositionexhibits a fogging content of about 500 μg/g or less as determined inaccordance with VDA 278:2002.
 4. The fiber-reinforced polymercomposition of claim 1, wherein the propylene polymer is a homopolymer.5. The fiber-reinforced polymer composition of claim 4, wherein thehomopolymer is metallocene-catalyzed.
 6. The fiber-reinforced polymercomposition of claim 1, wherein the propylene polymer is anα-olefin/propylene copolymer.
 7. The fiber-reinforced polymercomposition of claim 1, wherein the composition includes a blend of apropylene homopolymer and an α-olefin/propylene copolymer.
 8. Thefiber-reinforced polymer composition of claim 7, wherein the homopolymeris metallocene-catalyzed.
 9. The fiber-reinforced polymer composition ofclaim 1, wherein the propylene polymer has a melt flow index of about150 grams per 10 minutes or more as determined in accordance with ISO1133-1:2011 at a load of 2.16 kg.
 10. The fiber-reinforced polymercomposition of claim 1, wherein the fibers are glass fibers.
 11. Thefiber-reinforced polymer composition of claim 1, wherein the fibersconstitute from about 20 wt. % to about 60 wt. % of the composition. 12.The fiber-reinforced polymer composition of claim 1, wherein the fibersare oriented in a longitudinal direction of the composition.
 13. Aninjection molded part comprising the fiber-reinforced polymercomposition of claim 1, wherein the part has a wall thickness of about2.5 millimeters or less.
 14. An automotive part comprising afiber-reinforced polymer composition comprising a polymer matrix thatcontains a propylene polymer and a plurality of long reinforcing fibersthat are distributed within the polymer matrix, wherein the polymercomposition exhibits a spiral flow length of about 450 millimeters ormore as determined in accordance with ASTM D3123-09, and further whereinthe composition exhibits a volatile organic content of about 100 μgC/gor less as determined in accordance with VDA 277:1995.
 15. Theautomotive part of claim 14, wherein the composition exhibits a tolueneequivalent volatile organic content of about 250 μg/g or less asdetermined in accordance with VDA 278:2002.
 16. The automotive part ofclaim 14, wherein the composition exhibits a fogging content of about500 μg/g or less as determined in accordance with VDA 278:2002.
 17. Theautomotive part of claim 14, wherein the propylene polymer is ahomopolymer.
 18. The automotive part of claim 17, wherein thehomopolymer is metallocene-catalyzed.
 19. The automotive part of claim14, wherein the propylene polymer is an α-olefin/propylene copolymer.20. The automotive part of claim 14, wherein the composition includes ablend of a propylene homopolymer and an α-olefin/propylene copolymer.21. The automotive part of claim 20, wherein the homopolymer ismetallocene-catalyzed.
 22. The automotive part of claim 14, wherein thefibers are glass fibers.
 23. The automotive part of claim 14, whereinthe fibers constitute from about 20 wt. % to about 60 wt. % of thecomposition.
 24. The automotive part of claim 14, wherein the fibers areoriented in a longitudinal direction of the composition.
 25. Theautomotive part of claim 14, wherein the part has a wall thickness ofabout 2.5 millimeters or less.
 26. The automotive part of claim 14,wherein the part is injection molded.
 27. The automotive part of claim14, wherein the part is an interior automotive part.
 28. The automotivepart of claim 27, wherein the part is a pedal module, instrument panel,arm rest, console, seat structure, interior module, lift gate, interiororganizer, step assist, ash tray, glove box, gear shift lever, or acombination thereof.
 29. The automotive part of claim 14, wherein theautomotive part is an exterior automotive part.
 30. The automotive partof claim 29, wherein the exterior automotive part is a fan shroud,sunroof system, door panel, front end module, side body panel, underbodyshield, bumper panel, cladding, cowl, spray nozzle body, capturing hoseassembly, pillar cover, rocker panel, or a combination thereof.